import java.math.BigInteger;

public class Test {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		//for (int i = 1; i <= 20; ++i)
			System.out.println(25+": "+factorial(25));
	}

	public static BigInteger factorial(int n) {
		BigInteger p = BigInteger.valueOf(1);
		while (n > 0)
			p = p.multiply(BigInteger.valueOf(n--));

		return p;
	}

}
